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Electron and photons time of flight

  1. Mar 7, 2009 #1

    I would be interrested by some references comparing times of flight for photons and electrons.
    Ideally, I would like to see that for different energies.
    I would also prefer astrophysical sources, since the huge distances should increase the precision.

  2. jcsd
  3. Mar 7, 2009 #2
    Photons have no mass, and travel at c. Electrons have a small mass and can travel at any speed less than c. Perhaps you meant electrons from some specific source.
  4. Mar 7, 2009 #3
    Let's consider massive particles and photons emitted at the same time from a very distant astronomical source.
    The delay between these pulse should be related to the energy of the particles.
    I wonder if such data would be available.
    In principle this should match the E(v) relation from Special Relativity.

    However, there are difficulties:

    - charged particles are likely much more dispersed than neutral particles, but they may have longed lifetimes, e-, p+
    - neutrons have a lifetime of only 15 min roughly, they could not come from very far

    Maybe solar events could be canidates?
  5. Mar 7, 2009 #4
    Wikipedia says that solar wind is 400-750 km/s. That is 0.25% of c. So it would take 400 times as long for electrons from solar wind to travel as photons from the Sun.
  6. Mar 7, 2009 #5


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    Er... why does this have to be "astrophysical sources"? In a particle accelerator, when an arcing occurs during, say, conditioning, you always get the light first and then the burst of charge later.

    Is there something that you are trying to get at? I mean, it appears as if this is rather obvious and isn't even a "relativity" issue.

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